When plugin is executed with a DEL command, it does not
print result to stdout unless there is an error. Therefore
it stdout bytes should not be passed to json.Unmarshal.
This takes some of the machinery from CNI and from the rkt networking
code, and turns it into a library that can be linked into go apps.
Included is an example command-line application that uses the library,
called `cnitool`.
Other headline changes:
* Plugin exec'ing is factored out
The motivation here is to factor out the protocol for invoking
plugins. To that end, a generalisation of the code from api.go and
pkg/plugin/ipam.go goes into pkg/invoke/exec.go.
* Move argument-handling and conf-loading into public API
The fact that the arguments get turned into an environment for the
plugin is incidental to the API; so, provide a way of supplying them
as a struct or saying "just use the same arguments as I got" (the
latter is for IPAM plugins).
Luckily the docs haven't mentioned support for ipMasq for both plugins so far.
Even if anyone has attempted to enable the feature in their configuration files it didn't have the desired effect for the network.
A specific IP can now be requested via the environment variable CNI_ARGS, e.g.
`CNI_ARGS=ip=1.2.3.4`.
The plugin will try to reserve the specified IP.
If this is not successful the execution will fail.
Instead of temp (random) name, the final name (e.g. eth0)
was used during link creation. This would collide on hosts
that already had the an interface with such a name.
The dhcp daemon may be running with a different cwd
and so the netns paths need to be absolute. This patch
also refactors the code to pull out the common, RPC
parts, out into a separate function.
Path rewriting causes too many problems when vendoring
vendored code. When CNI code is vendored into rkt,
godep has problems code already vendored by CNI.
This introduces a notion of a "meta" plugin. A meta plugin
is one that delegates the actual work of setting up the interface
to the main plugin. The meta plugin is used to select and dynamically
configure the main plugin. The sequence of events, is as follows:
Given netconf like:
{
"name": "mynet",
"type": "flannel",
"delegate": {
"type": "bridge"
}
}
flannel fills in values like "mtu", "ipam.subnet" and delegates to
"bridge" main plugin. "bridge" plugin will operate as usual, calling
into ipam module for IP assignment.
Delegate dictionary should not contain "name" field as it will be
filled in by the flannel plugin.
When plugin errors out, it prints out a JSON object to stdout
describing the failure. This object needs to be propagated out
through the plugins and to the container runtime. This change
also adds Print method to both the result and error structs
for easy serialization to stdout.
